Authoritarianism

After a recent conversation about the downfall of Aleppo and the Middle East, the topic of Authoritarianism and political/social stability arose. Do Authoritarian regimes bring about more stability than democracies? And if it weren't for the western intervention in the Middle East would there be more stability in the region? In order for me to assess the differences between the two political systems I decided to chose a Authoritarian regime that was relatively neutral to western tampering, thus I decided to make a comparison between China (the upcoming supposed powerhouse) and the current superpower the US, and how they both combat terrorism and which is more effective in mitigating (reducing) threats of terrorism.